Our trial will involve recruiting patients who have unresectable pancreatic cancer and who are suitable for the current standard of care which is gemcitabine chemotherapy. They will be assessed for suitability and then offered entry into the trial. This essentially consists of a 4 hour long infusion of purified omega-3 fish oil immediately after their gemcitabine chemotherapy has finished. This will occur once a week for three weeks, with a rest on the fourth week. The cycle then continues until the cancer has shown progression on a CT scan, the gemcitabine chemotherapy is stopped due to toxicity or the patient withdraws or dies. CT scans to assess this are performed every 2 months. Blood tests will be taken before and after each treatment and analysed for changes in inflammatory markers. The patients will be asked to fill in a quality of life and pain questionnaire each week during the 4 hour infusion.